LONDON - High levels of malnutrition and the difficulties of delivering aid make Somalia the world's most pressing humanitarian crisis, the U.N. refugee agency's representative there said on Tuesday.

More than 1 million people have fled their homes in Somalia, which is convulsed by fighting between Ethiopian-backed government forces, Islamist insurgents and an assortment of warlords.

"I've never seen anything like Somalia before," Guillermo Bettocchi, representative of the U.N. High Commissioner for Refugees, said during a visit to London.

Malnourished child Zara Mahmoud, 2, whose younger brother died, is being comforted by her mother at Hartesheik camp for internally displaced persons in the Somali Region of Ethiopia April 29, 2005. (REUTERS/Handout/Files)

"The situation is very severe. It is the most pressing humanitarian emergency in the world today -- even worse than Darfur," he told reporters, referring to the war in western Sudan, which has driven 2.5 million from their homes.

A bomb attack which killed three foreign aid workers in Somalia on Monday underlined the difficulty in delivering aid in the anarchic country that has been wracked by clan violence for 17 years, he said.

Fifteen percent of the population suffer acute malnutrition while health services are very limited and sanitation, water and shelters are extremely poor, Bettocchi said.